title: Attention-driven auditory cortex short-term plasticity helps segregate relevant sounds from noise.
abstract: How can we concentrate on relevant sounds in noisy environments? A "gain model" suggests that auditory attention simply amplifies relevant and suppresses irrelevant afferent inputs. However, it is unclear whether this suffices when attended and ignored features overlap to stimulate the same neuronal receptive fields. A "tuning model" suggests that, in addition to gain, attention modulates feature selectivity of auditory neurons. We recorded magnetoencephalography, EEG, and functional MRI (fMRI) while subjects attended to tones delivered to one ear and ignored opposite-ear inputs. The attended ear was switched every 30 s to quantify how quickly the effects evolve. To produce overlapping inputs, the tones were presented alone vs. during white-noise masking notch-filtered ±1/6 octaves around the tone center frequencies. Amplitude modulation (39 vs. 41 Hz in opposite ears) was applied for "frequency tagging" of attention effects on maskers. Noise masking reduced early (50-150 ms; N1) auditory responses to unattended tones. In support of the tuning model, selective attention canceled out this attenuating effect but did not modulate the gain of 50-150 ms activity to nonmasked tones or steady-state responses to the maskers themselves. These tuning effects originated at nonprimary auditory cortices, purportedly occupied by neurons that, without attention, have wider frequency tuning than ±1/6 octaves. The attentional tuning evolved rapidly, during the first few seconds after attention switching, and correlated with behavioral discrimination performance. In conclusion, a simple gain model alone cannot explain auditory selective attention. In nonprimary auditory cortices, attention-driven short-term plasticity retunes neurons to segregate relevant sounds from noise.
authors.affiliation: Harvard Medical School-Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.forename: Matti
authors.initials: M
authors.lastname: Hämäläinen
authors.forename: Iiro P
authors.initials: IP
authors.lastname: Jääskeläinen
authors.forename: Seppo P
authors.initials: SP
authors.lastname: Ahlfors
authors.forename: Samantha
authors.initials: S
authors.lastname: Huang
authors.forename: Fa-Hsuan
authors.initials: FH
authors.lastname: Lin
authors.forename: Tommi
authors.initials: T
authors.lastname: Raij
authors.forename: Mikko
authors.initials: M
authors.lastname: Sams
authors.forename: Christos E
authors.initials: CE
authors.lastname: Vasios
authors.forename: John W
authors.initials: JW
authors.lastname: Belliveau
mesh_terms: D001288:Attention; D001303:Auditory Cortex / Q000502:physiology*; D004569:Electroencephalography; D006801:Humans; D008279:Magnetic Resonance Imaging; D009473:Neuronal Plasticity; D009622:Noise